The isolation and characterization of normal and abnormal proteins in genetic disorders affecting the nervous system permits the isolation of cDNA and genomic DNA that can be used to correct inherited protein deficiencies using gene therapy. Particularly suited for initial attempts at gene therapy are those disorders (such as Gaucher disease, the most common sphingolipidosis) in which the systemic and neurologic manifestations of the disorder are the consequences of abnormalities of hematopoietic cells, like the macrophage. In these instances that transfer of normal genes to either specific tissue or bone marrow progenitor cells is a rationale therapeutic approach. Using the lysosomal disorder Gaucher disease as a model, we utilized retroviral vectors to transfer and express human glucocerebrosidase in mouse and Gaucher patient cell lines. The complete correction of glucocerebrosidase activity in Gaucher fibroblasts in culture has provided the impetus for evaluation of retroviral mediated gene transfer of the glucocerebrosidase gene into a mouse model of Gaucher disease. Retroviral mediated transfer of tyrosine hydroxylase for the correction of DOPA deficiency states is also studied. Receptor mediated gene transfer into tissues is also being investigated. The initial goal of this research is the application of gene therapy to the non-neuronopathic phenotypes. Transgenic animal models are developed using targeted homologous recombination in embryonic stem cells to generate mouse models of human disease. Recombinantly manipulated cells that act as depots of L- DOPA release are used for transplantation into the nervous system of animal models. When our understanding of the pathogenic mechanisms of inherited neurological and psychiatric diseases improves and as retroviral-mediated expression of genes in specific tissues and cells becomes more predictable, we can extend the use of gene therapy to treatment of selected disorders affecting the nervous system.